The present invention relates to interconnection of the combustors in combustion apparatus such as gas turbines, and more particularly to an improved crossover tube for such connections.
Gas turbines include a combustion chamber disposed between a compressor section and a turbine section. The combustion chamber is usually of annular cross section with a plurality of combustors disposed in it. Combustion air is supplied by the compressor to the combustion chamber from which it flows into the combustors which are generally cylindrical members or baskets with a fuel supply and burner at one end and with suitable holes for the entrance of air. A plurality of combustors is provided and they are arranged side-by-side in an annular array extending around the combustion chamber. During operation, fuel is burned in the combustors to provide a supply of hot pressurized gas which is directed to the turbine section which drives the compressor and the output shaft.
The combustors are usually interconnected, each combustor having a tubular connection to the two adjacent combustors on opposite sides. Only one or two ignition devices are then needed to ignite all the combustors, the flame propagating through the interconnections from each combustor to the next. The interconnections between combustors usually comprise metal crossover tubes to provide communication between the combustors and it is necessary to provide for some misalignment between the corresponding connections of the adjacent combustors. Such misalignment may occur because of the necessary dimensional tolerances, and unavoidable thermal distortions, which make it difficult to insure exact alignment of the connectors on adjacent combustors. Heretofore, various expedients have been used to accommodate misalignment, such as flanged attachment means with spherical seats, and transversely slidable connections, but such expedients have not been satisfactory because of their limited ability to permit misalignment and because they are expensive and difficult to assemble. The interconnections should also allow thermal expansion and contraction of the parts and this further complicates the problem.